Protein phosphatase 5 modulates SMAD3 function in the transforming growth factor‐β pathway

► PP5 interacts with SMADs2 and 3. ► TGFβ pathway signaling is enhanced in PP5-null MEFs. ► PP5 controls the levels of SMAD3 protein but not transcripts in MEFs. ► PP5 catalytic activity is essential for its control of SMAD3 levels in MEFs.